The technique developed during the past grant period for amino acid sequencing of peptides in the complex mixtures encountered in the determination of the primary structure of proteins is to be utilized for the confirmation of the proposed structure of neocarzinostatin, a protein of 109 amino acids exhibiting antitumor and antibiotic activity, and of collagenase A. Because of the latter's action on the ubiquitous structural protein, collagen, its primary structure is of great interest. Collagenase A appears to consist of about 1000 amino acid residues and thus represents not only a severe test of the method but also provides ample opportunity for its further improvement and refinement as the work proceeds. Goals in that direction involve further increase in speed, sensitivity and efficiency, particularly through refinement (perhaps even automation) of the chemical steps, and computer-aided interpretation of the data.